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x86/sev: Require the RMPREAD instruction after Zen4

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Limit usage of the non-architectural RMP format to Zen3/Zen4 processors.
The RMPREAD instruction, with architectural defined output, is available
and should be used for RMP access beyond Zen4.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Reviewed-by: Ashish Kalra <ashish.kalra@amd.com>
Link: https://lore.kernel.org/r/5be0093e091778a151266ea853352f62f838eb99.1733172653.git.thomas.lendacky@amd.com
This commit is contained in:
Tom Lendacky 2024-12-02 14:50:48 -06:00 committed by Borislav Petkov (AMD)
parent 0cbc025841
commit 4972808d6f
1 changed files with 7 additions and 2 deletions
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9
arch/x86/kernel/cpu/amd.c
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@ -355,10 +355,15 @@ static void bsp_determine_snp(struct cpuinfo_x86 *c)
/*
* RMP table entry format is not architectural and is defined by the
* per-processor PPR. Restrict SNP support on the known CPU models
* for which the RMP table entry format is currently defined for.
* for which the RMP table entry format is currently defined or for
* processors which support the architecturally defined RMPREAD
* instruction.
*/
if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
c->x86 >= 0x19 && snp_probe_rmptable_info()) {
(cpu_feature_enabled(X86_FEATURE_ZEN3) ||
cpu_feature_enabled(X86_FEATURE_ZEN4) ||
cpu_feature_enabled(X86_FEATURE_RMPREAD)) &&
snp_probe_rmptable_info()) {
cc_platform_set(CC_ATTR_HOST_SEV_SNP);
} else {
setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);